The mechanism of synergistic hormone interaction is being studied utilizing specific protein synthesis induced by steroid and terpenoid hormones both in vivo and in vitro. Specific protein synthesis is being studied in wing tissue at short time intervals (minutes) after ecdysone or ecdysone plus juvenile hormone administration to pupae of Hyalophora cecropia to learn about early biochemical events and at various times (days) after target tissue responds to the hormone(s) in order to study the effects of the hormone(s) on the developmental sequence of structural protein synthesis. These studies are utilizing the technique of amino acid incorporation into specific proteins as determined from double label isotope experiments analyzed by gel electrophoresis and subsequent plotting of H3/C14 ratios of gel slices. In conjunction with specific protein synthesis, the binding of H3-ecdysterone and H3-juvenile hormone to cytoplasmic and nuclear components of target tissues is also being studied in order to correlate nuclear events with a biological response. The stimulation and/or repression of RNA polymerase by ecdysone and juvenile hormone is being investigated. These studies will aid in our understanding of the mechanism of action of steroid and terpenoid hormones and the regulation of cellular growth and differentiation. BIBLIOGRAPHIC REFERENCES: Ruh, T.S., S.G. Wassilak, M.F. Ruh. Androgen-induced nuclear accumulation of estrogen receptor. Steroids, 25: 257, 1975; Ruh, T.S., and M.F. Ruh. Androgen induction of a specific uterine protein. Endocrinology, October, 1975.